Box2d Revisited: "When I look at the graph above, the first thing that sticks out is that there are two obvious performance clusters. If you ignore AS3 for a moment, you’ll notice that there’s a cluster right around 1-2x native, and another broadly centered on 10x native. These clusters correspond to the “static” and “dynamic” VMs, respectively (I’m aware I’m abusing these terms a bit, but I believe they capture a fairly fundamental difference between, say, the JVM and a Javascript VM). You might also notice that the variance in each VM’s performance is closely related to its mean – in other words, the slower they are, the more unpredictable they are."